The present invention relates to an image transfer unit used for connecting a copy machine or the like with a facsimile apparatus, an SCSI board and a memory unit, through a bus, and an image forming apparatus using the image transfer unit.
Conventionally, an image forming apparatus such as a copying machine is capable of expanding functions by connecting options such as a printer, a facsimile apparatus, an SCSI board, a memory unit. In this case, if a general purpose bus such as an ISA bus is used, standard parts can advantageously be used with ease. An option such as a printer or a facsimile apparatus generally uses only a small memory space, and therefore, can be directly connected through a general purpose bus such as an ISA bus.
However, an image memory such as a page memory requires a memory size equivalent to at least one page of image, which is larger than the memory space for a general purpose bus such as an ISA bus. In this case, it is impossible to directly connect the image memory and a general purpose bus such as an ISA bus having a small memory space to a system bus of the image forming apparatus. To connect the image memory and the general purpose bus such as an ISA bus to the system bus, components such as an address decoder are required.